I messaged them and they told me that Travelnest and Airbnb are already partner sites, meaning that if you are on Airbnb you are also automatically on Travelnest....however, this doesn't seem like it is the case when they have told you something different. I agree that greater exposure is definitely needed as there are so many companies out that doing the same thing. However, my advice would be to stick with Airbnb and when you feel more confident may be sign up elsewhere. There are quite a few things about using different domains that could make life a bit complicated .....This however, is just my opinion for what it is worth. Good luck and if you get the answer to your question please post it on here!!